This invention relates generally to fluid transport systems and, more particularly, to methods and apparatus for using an electrical machine to transport fluids through a pipeline.
Fluid transport is used in a variety of different industries including, but not limited to the chemical, oil and gas industries. In one known fluid transport application fluids are transported from on-shore or off-shore locations to processing plants for subsequent use. In other known applications, fluid transport is used in hydrocarbon processing industries and chemical industries, and to facilitate distribution to end-users.
At least some known fluid transport stations use fluid transport apparatus such as compressors, fans and/or pumps that are driven by gas turbines. Some of these turbines drive the associated fluid transport apparatus via a gearbox that either increases or decreases a gas turbine output drive shaft speed to a predetermined apparatus drive shaft speed. Electrical machines (i.e., electrically-powered drive motors, or electric drives) may be advantageous over mechanical drives (i.e., gas turbines) in operational flexibility (variable speed for example), maintainability, lower capital cost and lower operational cost, better efficiency and environmental compatibility. Additionally, electric drives are generally simpler in construction than mechanical drives, generally require a smaller foot print, may be easier to integrate with the fluid transport apparatus, may eliminate the need for a gearbox, and/or may be more reliable than mechanical drives.
However, systems using electric drives may be less efficient than those systems using mechanical drives. At least some factors affecting electric drive efficiency include motor drive and drive controls electrical and electronic topologies, electrical power source quality and efficiency, size and weight of electric drive components (rotors for example) and magnetic coupling strength. Moreover, fluid transport apparatus electric drives generate heat via the drive components, via windage losses associated with the rotors for example, and may require supplemental systems to facilitate heat removal. For example, some known electric drives use the fluid being transported as the primary heat transfer medium and channel the fluid through and around the stator. However, in some cases, the fluid being transported may have aggressive constituents or impurities which may adversely affect the efficiency of the components being used.